A horizontal spring has one end firmly attached to a wall and the other end attached to a mass. The mass can slide freely on a smooth, horizontal surface with no friction. The mass is pulled away from the equilibrium position by a distance A in the positive x-direction and then released. At which position is the kinetic energy of the mass-spring system a maximum?

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?